There is no objective evidence, since you have removed the offending agents, that this is infectious, or an immune problem.
However, this can well be hyperactive pelvic function, and the correct therapy, or even acupuncture, can settle that down.
Correct bowel flora might settle this down as well, as this has multiple effects.
I suggest you take her to a functional medicine specialist, these MDs are trained beyond their own specialty, and I am sure there are plenty of family doctors and pediatricians who are certified now.
You can find a list of evidence based natural medicine doctors here
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